Technical Field
The present invention relates to a low-temperature device for separating and purifying gas, and particularly to a low-temperature device for separating and purifying gas based on a small-sized low-temperature refrigerating machine.
Related Art
Separation and purification of component gases in an impurity-containing feed gas are basic processes of obtaining a high-purity (the volume percentage is 99.999% or above) gas. Typically, the separation is performed by using a difference between condensing temperature and molecular properties of the component gases, and the traditional methods include: distillation, segregation, adsorption, catalytic reaction, and the like. When a product gas requires higher purity, it is necessary to use several methods in combination, for example, a method of combining, high-pressure low-temperature condensation and low-temperature adsorption or a method of combining pressure swing adsorption at room temperature and low-temperature adsorption. The traditional separation and purification method has a complicated process and a high investment cost, and is typically used in large gas separation and purification equipment.
Generally, separation and purification of helium, neon and other inert gases are also based on the foregoing several common methods. In inert gases, helium, neon and other inert gases have very important applications in fields such as aviation, aerospace, military and scientific research, and the demand increases day by day. What is important is that our comity belongs to countries poor in helium, and the United States as the world's major exporter of helium has listed helium as a strategic resource. Therefore, helium recycling is particularly important; besides, extraction from air separation units is one of the ways of obtaining helium and neon.
For recycled helium, its purity is about 90%, and the rest is mainly air and other impurity gases. The helium with the purity generally cannot be directly used, and needs to undergo a particular separation and purification process. For separation and purification of helium and neon in air separation units, the traditional method generally includes three working procedures, i.e., extraction of crude helium-neon gas mixture, preparation of pure helium-neon gas mixture, and preparation of pure helium and pure neon. The three working procedures all have a complicated process and a high investment cost, lack economy, and are rarely applied to actual air separation units.
The small-sized low-temperature refrigerating machine generally includes a GM refrigerating machine, a pulse tube refrigerating machine, a Stirling refrigerating machine, a J-T refrigerating machine and the like. A refrigerating temperature of the small-sized low-temperature refrigerating machine is generally in a range of 0-80K (−273.15° C.-193.15° C.), and the refrigerating output is around 0.1-100 W. The small-sized low-temperature refrigerating machine is an important device for obtaining extremely low temperature. The low-temperature device for separating and purifying gas based on the small-sized low-temperature refrigerating machine is applicable to small-scale gas separation and purification.